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block: respect BLK_MQ_F_NO_SCHED 

If one driver claims that it doesn't support io scheduler via
BLK_MQ_F_NO_SCHED, we should not allow to change and show the
availabe io schedulers.

This patch adds check to enhance this behaviour.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Ming Lei 2017-04-15 20:38:22 +08:00 committed by Jens Axboe
parent 005882e53d
commit 3a5088c8c1
1 changed files with 10 additions and 2 deletions
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12
block/elevator.c
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@ -1098,12 +1098,20 @@ int elevator_change(struct request_queue *q, const char *name)
}
EXPORT_SYMBOL(elevator_change);
static inline bool elv_support_iosched(struct request_queue *q)
{
if (q->mq_ops && q->tag_set && (q->tag_set->flags &
BLK_MQ_F_NO_SCHED))
return false;
return true;
}
ssize_t elv_iosched_store(struct request_queue *q, const char *name,
size_t count)
{
int ret;
if (!(q->mq_ops || q->request_fn))
if (!(q->mq_ops || q->request_fn) || !elv_support_iosched(q))
return count;
ret = __elevator_change(q, name);
@ -1135,7 +1143,7 @@ ssize_t elv_iosched_show(struct request_queue *q, char *name)
len += sprintf(name+len, "[%s] ", elv->elevator_name);
continue;
}
if (__e->uses_mq && q->mq_ops)
if (__e->uses_mq && q->mq_ops && elv_support_iosched(q))
len += sprintf(name+len, "%s ", __e->elevator_name);
else if (!__e->uses_mq && !q->mq_ops)
len += sprintf(name+len, "%s ", __e->elevator_name);